Sprue for centrifugal molds



3 Sheets-Sham'I 1 INVENTOR. FEL LTTO/V BY A TTOR/VEV Sept. 20, 1949. F. B. LrrToN sPRUE Fon CENTRIFUGAL Moms Filed Deo. 21, 1945 Sept. 20, 1949. F. a. LrrToN SPRUE FOR CENTRIFUGAL MOLDS 3 Sheets-Sheet 2 Filed Dec. 2l, 1945 INVENTOR. FEUX i/TTN TTRNEV Sept. 20, 1949. F. B. LITT'oN,

SPRUE Fon CENTRIFUGAL Mams 3 $heeLS-Sheet 3 *Y Filed Dec. 2l, 1945 l APM V /l J Patented Sept. 20, 1949 SPRUE FOR CENTRIFUGAL MOLDS Felix B. Litton, Detroit, Mich., assigner to Bendix Aviation Corporation, Detroit, Mich., a corporation of Delaware Application December 21, 1945, Serial No. 636,294

4 Claims. (Cl. 22-134) This invention relates to foundry practices, and more particularly to the casting of metallic articles by pouring molten metals into a molding apparatus.

An object of the invention is to provide a new method of casting metallic articles.

Another object is to provide an improved venting method and means, effective to dispel all air and gas from a mold as the metalis poured therein.

Another object is to provide an improved molding apparatus for casting metallic articles, including articles the contours and/or semi-hollow internal structure of which present practicallly insurmountable obstacles to their production by conventional methods known to the prior arts.

Another object is to provide a molding apparatus for casting with the aid of centrifugal force.

Another object is to provide improvements in casting methods, a principal feature of which is the use of a series of core elements adapted to be inserted progressively in a drag. The cores are inserted in the drag prior to the casting operation, by simple procedure that requires no special skill for its performance; each core being tted (indexed) into a pre-designated position reserved for it. This indexing concept makes possible the production of articles of absolute uniformity, each article cast in a given apparatus being exactly the same, dimensionally, as its predecessor.

Other features of the invention reside in the specific structure and relationships of the parts employed to accomplish the casting operations, as hereinafter described. more fully, and as illustrated in the accompanying drawings.

It is to be understood, of course, that the drawings do not define the limits or scope of the invention, but merely illustrate how the invention may be practiced. The scope of the invention is as defined in the appended claims, which are to be construed as broadly as their language permits.

In the drawings: v

Fig. 1 is a central vertical sectional view of the molding apparatus by which the invention may be practiced;

Fig. 2 is a top plan view of the apparatus with certain parts cut away; f

Fig. 3 is an enlarged fragmentary view;

Fig. 4 is an enlarged fragmentary view of the core elements;

Fig. 5 is a transverse sectional view of the core assembly along the toe portions of the cores' fitting into the core indexing plate;

surface 36 having arededges.

Fig. 6 is an enlarged view of one of the core elements; and

Fig. '7 is an enlarged fragmentary view.

Referring to the drawings for more specic details of the invention Ill represents a base supporting a drag I2 having a rim I4. The base has a recess I6 in the bottom thereof and suitable means I8 are provided for the reception of fastening devices, and the rim of the drag has pivoted thereon thumb screws 20 arranged in spaced relation to one another.

The drag I2 has a cavity 22 contoured for the casting of radially' -bladed impellers, such as are commonly used in aircraft engine superchargers and the like. As shown, a core indexing plate 24 is fitted in the bottom of the cavity 22 and the rim I4 supports an indexing ring 26.

Non-metallic core elements 2B are supported in spaced relation to one another in the cavity 22 on the indexing plate 24 and the indexing ring 26. Each of the core elements 23 includes a nonmetallic body portion 30 having a metallic end 32 provided with a toe 34 and the outer end of the body portion is deformed to provide a flat The toes 34 on the metallic ends of the cores 28 are received by the slots 38, preferably arranged in keystone fashion, in the indexing plate 24. A bolt 40 extended through the inde-Xing plate and the base has an enlarged head 42 adapted to clamp the cores to the indexing plate, and shims 44 are tted between the adjacent edges of the flat surfaces 3S. This serves to properly space the cores in the cavity and to secure the cores against displacement.

A cope 46 superimposed on the drag I2 has spaced peripheral slots 48 for the reception of the pivoted thumb screw 20 on the drag I2, the thumb screws serving to secure the drag and cope together.

The cope 46 has a mold cavity 50 cooperating with the cavity 22 in the drag I2 to complete the mold. The cope 46 has a concentrically disposed opening 52 and an upwardly extended short sleeve 54 communicating with the opening. A removable tube 56 provided with spaced vents 58 has a iiange 60 at one end thereof. The tube 55 telescopes the short sleeve 54 and the flange 60 is secured to the cope 46 as by thumb screws 62.

A sprue 64 slipped in the tube 56 has spaced radially disposed lugs 66 seated on the free end of the short sleeve so as to support the sprue in spaced concentric relation to the short sleeve 54 and the tube 56. The sprue has a shoulder 68 for the reception of an inner tube 'I0 having an tube. 10 to the outer tube 56 is such that whenV molten metalis poured in the funnel 'H3` and enters Y the cavity of the mold by way of the lined tube 10 and the sprue 64 the air and gases in the cavity escape by way of the clearance or vented passage between the outer tube and the sprue and inner tube simultaneously with the entrance of theV molten metal into the cavity., i

Although the mold is illustrated as contoured for the casting of radially bladed impellers, the

ing hardening in their molds, and they are then fitted into position successively in the indexingY members. To assure uniformity on each use as above described, the cores should be numbered and the indexing slots 'correspondingly marked,

so that each slot and its Vmatched core remain readily identifiable.

Hlteference is made to Vco-pending application No. 609560,; fued VAugust s, 1945, disuosing an invention may, of course, be applied (by suitably I altering the contours of the parts) to the castingV of any other article the structure of Vwhich is such as to render desirable the use of the progressively inserted core principle of this invention, or the use of any of the related novel featuresv herein disclosed.

An important virtue of the indexed core assembly feature is that it makes possible the accurate casting of a plurality of blades, ribs, or other projecting surfaces of a single article, and assures accuracy without resort to or reliance upon tediously preparedv multi-contoured pat'- terns `or dies of the kind heretofore believed to be essential pre-requisites to the casting ofV such articles.

Moreover, the disclosed method and apparatus make it possible to add tremendously to the strength of radially bladed impellers, and the like, b-y providing them with reinforcing webs or shrouds along both front and rear edges of the several blades, rather than only along the rear edges, as in the prior art.

'Ihe invention thus facilitates production of, among other products, double shrouded impellers of the central inlet, peripheral outlet type, or the reverse thereof. Double-shrouded impellers are capable of withstanding stresses at speeds far'in excess of any heretofore attainable with the single-shrouded construction of the prior art; the added strength imparted by the additional shroud being the reason for the greater capabilities and capacity of an impeller cast by, the methods and with the apparatus herein disclosed.

After heating the apparatus by anyA suitable means, the assembly is placed upon a suitable spinning fixture (not shown) and rotated at a speed of approximately 325 R. P. M. The hot composition of molten metals .is poured into the funnel as this rotation proceeds, and as the pour-Y ing'approaches completion, the spinning is ac' celerated to approximately 425 R. P. M. (for the article cited for illustrative purposes) in order Yto reduce to a minimum the possibility of solidifying of any of the metal prior to complete filling of the narrower spaces near the periphery of the apparatus. As this filling with metal proceeds the air and gas in advance of the inflowing metal is forced into the annular path surrounding the sprue and inner tube and from there it escapes to the atmosphere.

The cores may be of any suitable material, preferahly a mixture of plastery and water. With a ratio of 80 grams of plaster to 47 grams of water, Ihave obtained a product which,upon hardening and drying, is substantially bubble free over its outer surface. The several cores are scraped to remove ridges that may have formed'.thereinfdur- 7 earlierembodiment of certain ofthe principlesV that are further developed in the present invention. s

-Having thus describedthe various features of the invention, what I claim as new and Vdesire to Asecure by Letters Patent is:

1. In a mold having a drag and a cope provid- ,in g in, conjunction with one another a mold cavity and a collar onthe cope communicating with the cavity, a perforated tube telescoping the collar, K

a sprue seated on the collar and extended into the cavity, a tube supported on the sprue in spaced relation to the perforated tube, and al funnel on the tube. Y

2. In a mold having a drag and a cope providing inV conjunction' with one another a mold cavity and a collar on the cope communicating with the cavity,a perforated tube fitted on the collar, a sprue having spaced lugs seated on the collar and suspendingvthe sprue in spaced concentric rela- :3 tion thereto, a tube supported on the spruein spaced concentric relation to the perforated tube, and a funnel supported on the tube. .Y

3.v In a mold having adrag and a cope providing in conjunction with one another a mold cavity and a collar on the cope-.communicating with the cavity, a perforated tube fitted on the collar, means securing the perforated tube to the cope, a sprue suspended in -the collar inspaced con--V centric relation thereto, a tube supported on the sprue in spaced relation to the perforated tube, anda funnel von the tube.

4. In a centrifugal mold having a drag and a cope providing in conjunction with one another a mold cavity and a ycollar on the cope communicating with the cavity, a perforated tube tted on the collar having a flange secured to the cope, ya

sprue having spaced lugs seated on the collar and Y suspending the sprue in spaced concentric relation to the collar and the perforated tube, a lined tube supported .on thev sprue having an enlarged end tted snugly in the perforated tubeand'a funnel supported on the enlarged end.

' Y FELIX B. LITTON.- A

REFERENCES CITED The following references Yare of record. in ,the

file-of 'this patent:

UNITED STATES PATENTS Henry Feb. 15, '1927 Anderson Julyv22, A19,30 Pike Jan, 23, 1934 Le Jeune Mar. 14,. 1939 Littmann `Sept.l2, 1939 IjIammond June 24, 1941 YHagemeyer Jan. 1'3, 1942 Pfeiffer Nov. `3, 1942 Greenberg. Mar. 6, 1945 FOREGN PATENTS Country v Date GreatA Britain Dec. 20, i926 Number 263,333

VSherbcndy May 10,1921 

